Pterygotus anglicus
Silurian eurypterid
Eurypterids are an extinct group of arthropods; their closest living relatives are probably horseshoe crabs. Though known by the name ’sea scorpions,’ they were not actually scorpions. They lived in aquatic (marine, brackish, and freshwater) and terrestrial environments from the Ordovician through the Permian Period.
Their many legs had different uses, but the last and largest pair were shaped like paddles, good for swimming about. Some eurypterids, like Pterygotus, also had large claws for catching prey.
Length: 16 inches